//     Zepto.js
//     (c) 2010-2016 Thomas Fuchs
//     Zepto.js may be freely distributed under the MIT license.

;(function ($, undefined) {
    var document = window.document,
        origShow = $.fn.show, origHide = $.fn.hide, origToggle = $.fn.toggle

    function anim(el, speed, opacity, scale, callback) {
        if (typeof speed == 'function' && !callback) callback = speed, speed = undefined
        var props = {opacity: opacity}
        if (scale) {
            props.scale = scale
            el.css($.fx.cssPrefix + 'transform-origin', '0 0')
        }
        return el.animate(props, speed, null, callback)
    }

    function hide(el, speed, scale, callback) {
        return anim(el, speed, 0, scale, function () {
            origHide.call($(this))
            callback && callback.call(this)
        })
    }

    $.fn.show = function (speed, callback) {
        origShow.call(this)
        if (speed === undefined) speed = 0
        else this.css('opacity', 0)
        return anim(this, speed, 1, '1,1', callback)
    }

    $.fn.hide = function (speed, callback) {
        if (speed === undefined) return origHide.call(this)
        else return hide(this, speed, '0,0', callback)
    }

    $.fn.toggle = function (speed, callback) {
        if (speed === undefined || typeof speed == 'boolean')
            return origToggle.call(this, speed)
        else return this.each(function () {
            var el = $(this)
            el[el.css('display') == 'none' ? 'show' : 'hide'](speed, callback)
        })
    }

    $.fn.fadeTo = function (speed, opacity, callback) {
        return anim(this, speed, opacity, null, callback)
    }

    $.fn.fadeIn = function (speed, callback) {
        var target = this.css('opacity')
        if (target > 0) this.css('opacity', 0)
        else target = 1
        return origShow.call(this).fadeTo(speed, target, callback)
    }

    $.fn.fadeOut = function (speed, callback) {
        return hide(this, speed, null, callback)
    }

    $.fn.fadeToggle = function (speed, callback) {
        return this.each(function () {
            var el = $(this)
            el[
                (el.css('opacity') == 0 || el.css('display') == 'none') ? 'fadeIn' : 'fadeOut'
                ](speed, callback)
        })
    }

})(Zepto)
